Blow The Gaff

Blow The Gaff : Phrases

Meaning:

To reveal a secret.

Example:

When we go to meet your father regarding your marriage, you have to keep mum. Do not blow the gaff.

Origin:

Gaff is related to be a variant of the Gab described in Gift of the gab and has nothing to do with the use of the word to describe a spar on a sailing ship, nor does it relate to the pole of the same name, which is based on the Portuguese gafe meaning boat-hook.